Turkish jets flew 33 sorties, hitting suspected bases of the Kurdistan Workers' Party (PKK), east of the Iraqi border city of Zakho. The PKK has been waging a bloody insurgency in support of a Kurdish homeland inside Turkey.
A Turkish army spokesman said 14 planes dropped 76 bombs and the targets were completely destroyed. He said all jets returned safely to base.
The dawn assault, unleashed on the eve of the Kurdish new year festival, followed weeks of gradual build-up in the region. The Turkish Prime Minister Tansu Ciller told the US President Bill Clinton in a 10-minute telephone conversation that Turkish soldiers were ordered "to safeguard civilian life and property," according to White House spokesman Mike McCurry. She promised a limited operation, he said. Mr Clinton expressed "his understanding for Turkey's need to deal decisively with PKK terrorism".
"We want to clear out this area and rip out the roots of the terror operations aimed at our innocent people," Ms Ciller said. "Utmost effort is being made not to harm civilians."
There was no word on casualties, but Iraqi Kurdish groups condemned the assault and said innocent civilians were being targeted. "The targeted area has no PKK bases and it is strictly populated by Iraqi Kurds," said the Kurdistan Democratic Party (KDP), which nominally controls the Iraqi border zone. The Iraqi National Congress, an opposition group which includes leading Kurdish factions, said Turkish soldiers had arrested hundreds of refugees as suspected PKK followers.
Most of northern Iraq is under the control of Iraqi Kurdish guerrillas who split from Baghdad after the Gulf war. A shield of Western air cover protects them from Iraqi government forces.
The Turkish army spokesman, Colonel Ihsan Ongun, said the troops planned to push 40 km (25 miles) into Iraq, along a 220km front, to attack more than 2,000 rebels. He said that 30,000 to 35,000 soldiers, mostly commandos and some from mechanised units, were taking part in the attack. They were to hit four PKK-controlled areas in northern Iraq, some of which had been identified by aerial photographs, the colonel said.
The Iraqi Kurds have complained that Turkish forces killed civilians in a similar cross-border drive against the PKK in 1992. Ankara says it killed about 1,800 Kurdish rebels from Turkey in that operation.
More than 15,000 people have been killed in Turkey since the PKK took up arms in 1984 in its campaign for a separate state. The drive against the PKK, which Turkish officials said was based on rights of "hot pursuit", was mounted on the eve of the Kurdish festival of Nowrouz - a traditional time of separatist protest. On Saturday, the PKK ambushed a 40-vehicle military convoy carrying 800 troops in eastern Turkey, killing 18 soldiers and challenging government claims that the rebels were all but finished.